In 2017, global oil demand grew at the fastest rate in a decade, rising to 1.5 million barrels a day according to a report from the International Energy Agency. This continued demand for oil and gas is pushing exploration and extraction deeper and further into remote regions of the world. Here, Graham Mackrell, managing director of Harmonic Drive UK, looks at the technological challenges and how high precision gearing is being increasingly used to drill deeper.
Lying in the western Pacific Ocean, south of Japan and north of New Guinea, is an archipelago known as the Mariana Islands. An unassuming collection of underwater volcanic peaks spanning a width of only 43 miles, it harbours the Mariana Trench, the deepest part of the world's oceans.
Although not many life forms survive down here, it's humbling to think that the oil extracted from thousands of wellheads in similarly deep abysses the world over, sustains the majority of human life on the surface above.
However, having exhausted reserves in many subsea oil fields, the pressure is now building on extraction companies to drill deeper and for longer, to obtain every last drop of the black gold. Existing equipment is not always rated for operation in the extreme temperatures, pressures and associated logistics of deep sea extraction.
This is creating technological challenges all the way from the top to the bottom of the supply chain. From topside platforms to subsea structures and all the way further downhole to the directional drill bit, original equipment manufacturers face the challenge of developing equipment that can withstand the harsh environment.
Having encountered these challenges over the last forty years in developing our precision gearing systems and actuators at Harmonic Drive, we're currently experiencing a growing demand from the oil and gas sectors as they move away from traditional hydraulic actuation systems towards electro-mechanical actuation systems. Gearing based electrical actuation is more economical, ecological, controllable and more reliable than traditional hydraulic actuation systems.
Starting topside, a single platform could be just one piece in a large extraction application spanning hundreds of miles. The positional antenna systems that enable radio communication between the platform, vessels and onshore teams often suffer from inaccuracy due to gearing with backlash characteristics.
This problem can be solved using a Harmonic Drive servo actuator. Its unique construction offers a combination of fixed circular spline, flexible spline and elliptical wave generator bearing, high reduction ratios can be achieved in a single stage. This simultaneously eliminates backlash and increases accuracy, all in a servo motor driven compact unit complete with feedback sensor.
As we leave the choppy surface of the sea and dive deeper, subsea applications vary from remotely operated vehicles (ROVs) all the way up to permanent subsea structures spread over many miles.
As cameras begin to be increasingly used in conjunction with robotic arms and manipulators on ROVs, we are seeing a growing trend of replacing hydraulic actuators with electric actuators to take advantage of the increased accuracy and controllability.
Finally, drilling through the seabed takes us downhole into the complex world of subsea oil fields. As the oil levels in shallow fields begin to diminish there is a drive to drill into deeper reserves. The problem is that the deeper oil is spread sporadically over vast distances, often in horizontal pockets. Using a continuous vertical wellbore is not feasible and so the concept of directional drilling was developed.
Rotary steerable systems (RSS) 'point-the-bit' technology uses Harmonic Drive component sets to vary the angle of inclination of the drill bit. This flexibility allows operators to achieve complex 3D well designs, connecting multiple marginal targets for high volume, efficient recovery. The high reduction ratio and annular design of the component makes it ideal for this application, with the inherent accuracy of the gear allowing tight control of wellbore placement and geo-steering.
As fossil fuels continue to diminish and our reliance on them increases, it will become essential that new exploration technologies are able to cope with the scorching temperatures, the crushing pressures and the harsh environment of deep sea extraction.